psychologywikiaorg-20200213-history
Dragonflies
A dragonfly is an insect belonging to the order Odonata, the suborder Epiprocta or, in the strict sense, the infraorder Anisoptera. It is characterized by large multifaceted eyes, two pairs of strong transparent wings, and an elongated body. Dragonflies are similar to damselflies, but the adults can be differentiated by the fact that the wings of most dragonflies are held away from, and perpendicular to, the body when at rest. Dragonflies possess six legs (like any other insect), but most of them cannot walk well. Dragonflies are valuable predators that eat mosquitoes, and other small insects like flies, bees, ants, and very rarely butterflies. They are usually found around lakes, ponds, streams and wetlands because their larvae, known as "nymphs", are aquatic. Etymology Anisoptera comes from the Greek meaning not, meaning equal, and meaning wings. Their hind wings are broader than their fore wings. Classification (Anisozygoptera) Formerly, the Anisoptera were given suborder rank beside the "ancient dragonflies" (Anisozygoptera) which were believed to contain the two living species of the genus Epiophlebia and numerous fossil ones. More recently it turned out that the "anisozygopterans" form a paraphyletic assemblage of morphologically primitive relatives of the Anisoptera. Thus, the Anisoptera (true dragonflies) are reduced to an infraorder in the new suborder Epiprocta (dragonflies in general). The artificial grouping Anisozygoptera is disbanded, its members being largely recognized as extinct offshoots at various stages of dragonfly evolution. The two living species formerly placed there — the Asian relict dragonflies — form the infraorder Epiophlebioptera alongside the Anisoptera. Dragonflies and damselflies Damselflies (suborder Zygoptera) are often confused with newly moulted dragonflies but once a dragonfly moults, it is fully grown. There are other distinctions that set them apart: most damselflies hold their wings at rest together above the torso or held slightly open above (such as in the family Lestidae), whereas most dragonflies at rest hold their wings perpendicular to their body, horizontally or occasionally slightly down and forward. Also, the back wing of the dragonfly broadens near the base, caudal to the connecting point at the body, while the back wing of the damselfly is similar to the front wing. The eyes on a damselfly are apart; in most dragonflies the eyes touch. Notable exceptions are the Petaluridae (Petaltails) and the Gomphidae (Clubtails). Life cycle mating]] Female dragonflies lay eggs in or near water, often on floating or emergent plants. When laying eggs, some species will submerge themselves completely in order to lay their eggs on a good surface. The eggs then hatch into nymphs. Most of a dragonfly's life is spent in the nymph form, beneath the water's surface, using extendable jaws to catch other invertebrates (often mosquito larvae) or even vertebrates such as tadpoles and fish.Head, Mandibles, and unusual Labium of Dragonfly Nymph (viewed from below)Dragonfly Nymph ZoologyDragonfly nymph eats guppy.Dragon fly larvae labium extended to capture prey They breathe through gills in their rectum, and can rapidly propel themselves by suddenly expelling water through the anus. Some nymphs even hunt on land, an aptitude which could easily have been more common in ancient times when terrestrial predators were clumsier. The larval stage of large dragonflies may last as long as five years. In smaller species, this stage may last between two months and three years. When the larva is ready to metamorphose into an adult, it climbs up a reed or other emergent plant. Exposure to air causes the larva to begin breathing. The skin splits at a weak spot behind the head and the adult dragonfly crawls out of its old larval skin, pumps up its wings, and flies off to feed on midges and flies. The larger dragonflies can live for 4 months in their flying stage. In flight the adult dragonfly can propel itself in six directions; upward, downward, forward, back, and side to side. The adult stage of larger species of dragonfly can last as long as twenty four hours. Behavior Feeding Mating Territorality Dragonflies in cultures In Europe, dragonflies have often been seen as sinister. Some English vernacular names, such as "devil's darning needle" and "ear cutter", link them with evil or injury. A Romanian folk tale says that the dragonfly was once a horse possessed by the devil. Swedish folklore holds that the devil uses dragonflies to weigh people's souls. The Norwegian name for dragonflies is "Øyenstikker", which literally means Eye Poker and in Portugal they are sometimes called "Tira-olhos" (Eye snatcher). They are often associated with snakes, as in the Welsh name gwas-y-neidr, "adder's servant". The Southern United States term "snake doctor" refers to a folk belief that dragonflies follow snakes around and stitch them back together if they are injured. bowl from Sikyatki archaeological site.]] For some Native American tribes they represent swiftness and activity, and for the Navajo they symbolize pure water. Dragonflies are a common motif in Zuni pottery; stylized as a double-barred cross, they appear in Hopi rock art and on Pueblo necklaces. They also have traditional uses as medicine in Japan and China. In some parts of the world they are a food source, eaten either as adults or larvae; in Indonesia, for example, they are caught on poles made sticky with birdlime, then fried in oil as a delicacy. In the United States dragonflies and damselflies are sought out as a hobby similar to birding and butterflying, known as oding, from the dragonfly's Latin species name, odonata. Oding is especially popular in Texas, where a total of 225 species of odonates in the world have been observed. With care, dragonflies can be handled and released by oders, like butterflies. Images of dragonflies are common in Art Nouveau, especially in jewelry designs. They also appear in posters by modern artists such as Maeve Harris. They have also been used as a decorative motif on fabrics and home furnishings. Japan As a seasonal symbol in Japan, the dragonfly is associated with late summer and early autumn. More generally, in Japan dragonflies are symbols of courage, strength, and happiness, and they often appear in art and literature, especially haiku. The love for dragonflies is reflected in the fact that there are traditional names for almost all of the 200 species of dragonflies found in and around Japan. Japanese children catch large dragonflies as a game, using a hair with a small pebble tied to each end, which they throw into the air. The dragonfly mistakes the pebbles for prey, gets tangled in the hair, and is dragged to the ground by the weight. As it symbolizes courage, boys are given the name of "Tombo", meaning dragonfly. The shape of the archipelago of Japan, as seen on a map, is said to be that of a dragonfly. Hence the leading male character in Kiki's Delivery Service, in a non-Japanese setting, is named "Tombo" so that the Japanese audience can identify with him. Beyond this one of Japan's former names – あきつしま (Akitsushima) – is literally an archaic form of Dragonfly Island(s).Nussbaum, Louis Frédéric et al. (2005). "Akitsushima" in This is attributed to a legend in which Japan's mythical founder, Emperor Jinmu, was bitten by a mosquito, which was then promptly eaten by a dragonfly. Nihonto See also * Elliot Pinhey * List of British dragonflies * Obelisk posture References External links * Tree of Life Odonata * * Identification key to dragonflies found in Ireland * British Dragonfly Society * Dragonflies and Damselflies (Odonata) of the United States * Phaon (Pinhey's Heritage African Odonata Network) * Dragonflies and damselflies on the UF / IFAS Featured Creatures Web site * Photos of dragonflies from Asia-dragonfly.net, Africa-dragonfly.net, America-Dragonfly.net, Libellulasman.com and Odonata.su * list of field guides to dragonflies, from the International Field Guides Database Category:Odonata Category:Dragonflies